1. Field of the Invention
The present invention relates to the mass production of thin, flexible lowcost circuits of arbitrarily definable shape. More particularly, the process according to the present invention is useful for the customized mass make of thin, planar Radio frequency [RF] resonant circuits including inductive and capacitive elements, as are commercially desired as marker means in Electronic Article Surveillance [EAS] systems, in Electronic Personnel Access Control [EPC] systems, in Electronic Anti-Counterfeit [EAC] systems, and in most modern Object Handling Control [OHC] systems, e.g. electronic document safe systems, clinical supply systems, electronic flight baggage and ticket control systems, and the like.
The invention further concerns the computerized nonstop mass production of such circuits for one time use, and breaks down prior art barriers in view of limitations for custom designs of shape, face, and resonant properties of such circuits. Custom designs of circuits are easily layouted onscreen of a modern personal computer The data obtained thereof are downloaded to the process line Hopping custom circuit and face designs with ease is unprecedentedly introduced. Forming tools have been abandoned. As an exclusive longlife production tool electromagnetic wave energy is extensively used. The circuits may be washed and sewn and attract their user with a pretty face.
U.S. Pat. No. 3,913,219 (LICHTBLAU) describes a production process for the make of planar electrical circuits comprising a dielectric sheet and having an inductively reacting conductive spiral path made from an appropriate metal foil and bonded to one side of said dielectric sheet. Said spiral path terminates, at each end, via at least one connection means, into first and second conductive areas being in a mutually aligned opposition and spaced by said dielectric sheet, thus forming a discrete capacitor. Said capacitor and said conductive spiral thus cooperate to form an LC resonant circuit The production method is tied to stringent problems and limitations, as follows:
Production starts up with a special trilayer material resulting from a difficult collamination process of two aluminum layers of widely differing thickness (typical 8 .mu.m and 50 .mu.m) with a polyethylene layer. The latter must exhibit very close tolerances in view of thickness (normally about of 25 .mu.m.+-.5 .mu.m) and dielectric permittivity, and hence has to be produced off-line, in a special apparatus, at extra speed, and thus is expensive. First waste results between its shock cooled high density extrusion and its heated collamination between said aluminum layers, at a considerably low speed. Then, applying known roto-printing techniques, etching resist patterns are printed, mutually in register, on both faces of the composition and dried, at high speed. Due to the roto-printing technique, the print is of the fixed formatted type, which means, the circuit patterns repeat at a constant pitch or spacing on the circumference of the printing cylinder. Though printing is performed with a high repetitive register accuracy of the resist structures defining the resonator to be constructed, a repetitive in-register condition is maintained only for a very short time from the following reason.
When etching, the entire processing web starts up shrinking, owing to strains frozen in the polyethylene during recrystallization in the early moment of its collamination with said aluminum layers aided by heat. These strains get active, once wide areas and spirally turn-to-turn spacings have been removed, and thus cancel a previously achieved in-register condition on the yet unetched web both in its along and across direction. Further, etching taken alone is a slow process step, since modern fast etching techniques--due to their inherent poor overetch protection--cannot be utilized. This is from the following reason. Etching must take place on both faces of the composition simultaneously, meaning, that the etching of aluminum layers having a widely different thickness (e.g. 8 .mu.m and 50 .mu.m) should be finished right at the same time. Overetching and out-of-register waste is the result.
Shrinking encounters the problem, that the endless processing web representing a plurality of resonant structures cannot be combined, as circuit's face, with an endless cover material preprinted with an individual outline per circuit repeating at a constant resonator pitch or space, since due to lost in-register condition no precise alignment of a resonantor and a preprinted circuit face (so as to mate and cover each other) can be maintained. Further, since the inconsistent multilayer construction of the fully finished circuit from other reasons can be printed merely asynchronously by aid of low quality rubber-flex techniques, this known process neither yields standard circuits printed in a fixed print-to-resonator register, nor yields circuits according to changing or hopping custom design specifications, e.g. including an attractive color print.
Further problems encounter with that method, since immediately a upon etching the processing web, due to its filigree shape, is most complicated to handle, to advance and to position, just in a state in which such should be facilitated and carried out quickly. Again waste is a result. For an improvement, it is not allowed to thicken the polyethylene layer for stabilization, otherwise the RF performance of resonators would dramatically drop provided such circuit should be made as small as possible which is, however, a common desire. Further problems encounter with the need, that the two metal layers have to be contacted through said polyethylene layer's normal thickness of of 25 .mu.m. Such thru-contacts proved to be unreliable; "dead" circuits use already to appear among good ones when shipped from the factory.
Chemical agents as being in worldwide use with the recreation of fashions and garments not only destroy these contacts. These agents dissolve and float off the roto-printable etchant resistive pattern, which is left back surplus in the circuit construction once etched. Hence, circuits of this make may even mediate or cause heavy degradations and deteriorations of suchlike treated fashions in a much later state, provided such circuits are made just for one way use for walking away with customer's buy. Moreover, though said polyethylene layer is considerable costly and its properties are essentially needed merely in a considerable small place of the entire resonator construction, this layer is very inefficient, since wasted over the entire circuit area (wasted precision is wasted money). As an overall result, these problems and the restrictions for the finished product concluded thereof qualifies this method as inapplicable for making disposable one way RF marker circuits, which also serve for quite other functions, a variety thereof having been disclosed in more recent patent applications of applicant.
U.S. Pat. Nos. 4,482,874 (RUBERTUS & TAIT) and U.S. Pat. No. 4,598,276 (TAIT) describe a method of producing novel high efficiency marker devices the unique design scheme of which having been taught in U.S. Pat. No. 4,694,283 granted to applicant. This method is based on a complex stamping routine which utilizes a most delicate domino stamping tool. It has a fixed design and requires steady performance control, service, and exchange on elapse of its short lifetime. This means, that such production cannot be run continuously 24 hours/365 days a year, at a minimum dead time. However, a minor advantage is obtained with this method over that mentioned above, so far as the pitch or spacing between resonators may be influenced at some degree, however, by encountering complex mechanics along the production line, provided such resonators should be covered in register with a paper face already on-line. However, owing to a limited dimensional precision of any cover material to join the endlessly produced resonator web, preprinting such cover material harvests all the same out-of-register problems with an attempt to have individual resonator structures superpose in a perfect alignment individual cover face prints.
U.S. Pat. No. 4,658,264 (BAKER) also repeats the basic construction scheme of the planar stripline resonator as disclosed in U.S. Pat. No. 4,694,283. However, it is not taught how to assign to such resonator a precisely registered print on its usable outer face, or how to design such resonator for facilitating its fitting between most modern cover materials, for giving it even a tex-like appearance or the capability of being washed and sewn. Oppositely, this Patent centers merely on the task of how to fold over a substantially filigree and inconsistent substrate for a registered alignment of folded over portions with a precision of alignment sufficient enough, as has been likely reflected in applicant's prior publications.
U.S. Pat. No. 4,369,557 (VANDEBULT) repeats major portions of the LICHTBLAU process, however, with an important distinction so far as the trilayer compound as a production carrier is exchanged for a dual layer one Thus, etching of a constant thickness metal layer is carried out merely on one face of a thin and dimensionally unstable dielectric layer which, however, again and all the same has to serve for production carrier's function. Consequently, all other problems and restrictions of the LICHBTLAU process are imported and maintained. Hence, that Patent does not teach how to produce one way RF marker circuits offering a modern cover face designed according to whatsoever customer's specifications.
European Patent Application No. 84104174.2 (SALAMONE, HOOVER & VANDEBULT) discloses a method of fabricating respective circuits by electrolytically depositing and growing up resonator structures. The process applies fixed format silk screen printing electrically conductive patterns on a thin dielectric film, as may be of polyester. Then, this film and patterns are subjected to a very slow electrolytic deposition routine. Since this method, too, does not yield a marketable product rather than mere (bare) resonators, it is also in conflict with the described out-of-register drawback, so that this process has also to be considered as off-limits for the mass production of RF marker circuits going both one way and customized, reading with a whatsoever pretty commercial face.
U.S. Pat. No. 2,943,966 (LENO and SEARLE) describes an inductive element formed by folding over an insulative sheet provided with conductive paths so that upon folding said paths configure as a coil which turns continuously. For this purpose, a conductive path may turn thru in its respective plane by 360 degrees. The insulative sheet is utilized for preventing short circuits between superposed conductive paths. The Patent does not refer to a fabrication of said insulative sheet, and refers neither to a dielectric layer provided on a face of conducutive paths nor to a precisely rated capacitance of a circuit, hence to no resonant feature of a finished circuit. No printed face as a "commercial face" is being referred to and definitely aligned with an "electrical face" of a carrier material.
U.S. Pat. No. 2,849,298 (WERBERIG) describes a process utilizing etching for forming conductive paths on a tenaceously adhering plastic film particularly in a way so that a slow compression betwewen heated platens leaves said conductive paths "embedded and locked in the laminate in flush relation thereto". The Patent does not refer to the make of a capacitor's dielectric layer, and hence refers neither to a dielectric layer provided on a face of conducutive paths nor to a precisely rated capacitance of a circuit, hence to no resonant feature of a finished circuit. No printed face as a "commercial face" is considered and definitely aligned with an "electrical face" of a carrier material. Obviously, Werberig did not think in terms of designing whatsoever condutor path patterns asynchronously, meaning, with a size an integer multiple of which does not equal a ion drum's circumference.
U.S. Pat. No. 3,526,573 (KEPPLE et al) describes a way of making flexible flame retardant foil-clad laminates having one or more printed circuits adhesively bonded to a flexible sheet made from a fibrous base material. Said base material may be impregnated and covered with a fully curved synthetic resin insulating material; the printed circuit composition does not deform when subjected to heat and exhibits an excellent dimensional stability.
U.S. Pat. No. 3,215,574 (KORB) describes a method for making thin flexible plastic-sealed printed circuits which utilizes, in a discontinuous additive manner, the temporary adherence (presence) of a fibrous material for stabilizing circuits under manufacture, for then beeing completely removed from the product in a later step.
The present invention not only accomplishes the object of overcoming the aforedescribed shortcomings and limitations.
It opens a new horizon for making mass marketable electrical circuits which feature custom designs and outfits to fill catalogs. Therefore, the present invention breaks with prior art methods, for thus defining a new reference standard of the state of the art, which becomes obvious from the listing of objects of the present invention, as follows:
Producing a continuous flow at constant process speed, no acceleration or deceleration of the production web, no rolling and unrolling of component materials; PA1 Abandoning spoolers; PA1 Abandoning forming tools; PA1 Abandoning the waste of precise and/or precious materials; PA1 Abandoning the production of construction materials off-line for having them imported on-line; PA1 Abandoning etching of metal layers having different thicknesses, once at a time; PA1 Abandoning out-of-register waste due to a shrinking or creasing production web; PA1 Abandoning unreliable electrical contacts; PA1 Abandoning close tolerance raw materials; PA1 Reducing heat stressings of the production carrier; PA1 Allowing less close tolerances of materials and/or structural components, thus utilizing inexpensive materials or components; PA1 Reusing waste to be recycled; PA1 Generating and/or feeding on-line vulnerable construction materials in a most late production state; PA1 Producing dielectric layers on-line on demand with properties just as currently required, and not accepting circuit's performance drop by misuse of such layers for carrier functions; PA1 Boosting thereby circuit's RF performance over prior art; PA1 Throwing off circuit all surplus materials which could lead to deterioration of fashions or garments due to their recreation; PA1 Utilizing a production carrier which can be handled precisely, at high speed, in any production step, under perfect position and register control; PA1 Allowing novel and modern cover materials in fashion and inexpensive paper as well as a production carrier; PA1 Making circuits having a tex- or tissue-like appearance and being resistive to attempts of tearing; PA1 Making RF marker circuits which can be washed and sewn; PA1 Registering an electrical circuit and a cover face print of such circuit thru the entire production line; PA1 Custom designing RF marker circuits with arbitrary shape, dimension, field layout and print face; PA1 Economically producing even smallest lots of circuits (e.g. a few hundreds) according to customer's specifications; PA1 Changing and fine-tuning designs of circuits in a short period of time or even at full production speed; PA1 Overcoming idea papers, drafts & drawings, scratch pads, models, layouts, films, microfiches for the design of whatsoever customized planar electrical circuit, and doing all of the design onscreen of a personal computer, and downloading for execution designs at full process speed; PA1 Utilizing graphics design & construction software (e.g. a desktop publishing software) on whatsoever personal computer on customer's site, and receiving customer's layout and design ideas as data frames via a communication line, and feeding customer personal designs into the production line, for a quick turnaround and shipment of customized circuits on same day or night; and PA1 Changing and hopping circuit designs at a freedom which is just the freedom to change News in the New York Times. PA1 GEM.TM. of Digital Research Inc., USA PA1 KEVLAR.TM. of E. I. Du Pont de Nemours & Co. (Inc.), USA PA1 Macintosh.TM. of Apple Computer Inc., USA PA1 TYVEK.TM. of E. I. Du Pont de Nemours & Co. (Inc.), USA PA1 THERMOTHEN.TM. of Maria Soell GmbH, FRG PA1 VAX.TM. of DIGITAL EQUIPMENT Corp., USA